Jetpack xml_rpc-32700 ERROR

Please check to make sure http://92.223.204.80/xmlrpc.php is working properly. It should show ‘XML‑RPC server accepts POST requests only.’ on a line by itself when viewed in a browser and should not have any blank links or extra output anywhere.

Although there is no blank line when looking at the file in the browser, doing a test query to that file returns some empty spaces before the response, thus chunking the last few characters of the response:

curl -A "Jetpack by WordPress.com" -is -H 'Content-Type: text/xml' --data '<?xml version="1.0"?><methodCall><methodName>demo.sayHello</methodName><params></params></methodCall>' 'http://92.223.204.80/xmlrpc.php' && echo
HTTP/1.1 200 OK
Content-Length: 181
Content-Type: text/xml; charset=UTF-8
Server: Microsoft-IIS/7.5
X-Powered-By: PHP/5.4.16
X-Powered-By: ASP.NET
Date: Wed, 18 Nov 2015 15:44:35 GMT
Connection: close

<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
  <params>
    <param>
      <value>
      <string>Hello!</string>
      </value>
    </param>
  </params>
</methodResp

Could you check for any spaces you may have added to your site’s wp-config.php, or to your theme’s template files, before the opening <?php tag?

This problem is theme’s related, I tried to upload a new theme and Jetpack connection works. This is strange btw because I didn’t touch a single .php theme file….

Since the problem is related to your theme, try checking every file for spaces before an opening PHP tag. It might be worth starting with the functions.php, as it can sometimes include code pasted from other sources.